120 FLORIDA GEOLOGICAL SURVEY-TWELFTH ANNUAL REPORT 
60-100 feet. 
100-200 feet. 
200-300 feet. 
300-350 feet. 
350-400 feet. 
400 feet. 
460 feet. 
470 feet. 
Chiefly gray sand marl. The sand grains are clear quartz 
held together by calcareous cement. 
Buff colored clayey marl, enough clay to become slippery when 
wet. One sample. 
Mixed sample including a greenish sandy marl and a light 
colored calcareous marl. 
Limestone. 
Gray clayey marl. One sample. 
Sample at 400 feet, is light colored limestone. 
Sample reported from 460 feet, is a smooth rounded black phos¬ 
phate nodule. Probably dropped from above. 
Light colored limestone. 
The samples from this well from 30-60 and 60-100 feet seem 
definitely to represent the Alum Bluff formation, which is thus un- 
expectelly near the surface at this place. 
The depth to the Eocene limestone in extreme western Florida 
has not been determined. From the character of samples reported 
from the well of the Southern States Lumber Company between 
Muscogee and Cantonment in Escambia County, described as 
“green clay,” it seems likely that the Eocene limestones there lie 
at a depth greater than 890 feet from the surface. The data re¬ 
garding substructure in that part of the State, however, is too lim¬ 
ited at present to be reliable. 
PENINSULAR FLORIDA. 
THE RELATION OF THE FLORIDA PENINSULA TO THE COASTAL PLAIN 
An unusual structural feature in coastal plains geology is the 
great Floridian plateau which, projecting from the mainland, 
separates the Atlantic Ocean from the Gulf of Mexico. The time 
of origin of this plateau may not be determinable, although it is 
now known to have been in existence and to have formed a large 
shallow water area as early at least as the Lower Cretaceous or 
Comanchean period. Although affected by diastrophic agencies, 
including elevation and depression, this plateau has continued as a 
structural feature from the Comanchean or earlier to the present 
time. 
